Nowadays, a successive approximation type AD converter circuit has been known as an AD converter circuit that is configured in a simpler form and is highly consistent with a CMOS process that enables lower-cost fabrication, and can realize usually-needed AD conversion time and conversion efficiency. Owing to its high consistency with the CMOS process and its smaller footprint, the successive approximation type AD converter circuit is incorporated in a microcontroller (MCU) in many cases. The successive approximation type AD converter circuit is proposed in, for example, following Patent Documents.
[Patent Document 1]    Japanese Unexamined Patent Application Publication No. Hei 4-220016
[Patent Document 2]    Japanese Unexamined Patent Application Publication No. 2005-86550
[Patent Document 3]    Japanese Unexamined Patent Application Publication No. Hei 7-264071
[Non-Patent Document 1]    http://edevice.fujitsu.com/jp/manual/MANUAL1/alllistj.html#WEB3, CM26-10107-1, MB95100A/H SERIES hardware manual